Many hybrid motor vehicles use two different batteries. One provides vehicle accessory power, and the other provides power to a drive motor. Such batteries are often isolated from each other electrically. A high-voltage battery can also be isolated from the vehicle's chassis or reference potential.
When wiring from the high voltage battery for the drive motor is routed throughout the vehicle, physical damage to the conductors that extend between the battery and the drive motor can frequently cause leakage current to flow between that battery and the vehicle's primary battery. A leakage current can also exist when connections between individual cells comprising a high-voltage battery are shorted to ground. A method and an apparatus for detecting and quantifying a leakage current flowing between two normally disconnected batteries would be an improvement over the prior art.